HMRC registration and solicitors: why this matters, and what Infolegal is doing to help
The HMRC decision to introduce a mandatory registration regime for advisers who interact with it on behalf of clients is one of those developments that looks deceptively technical at first glance, but which has the potential to affect a very large proportion of solicitors’ firms in quite practical ways. While the headlines have tended to focus on conveyancers and Stamp Duty Land Tax, the reality is that this is a much wider change that cuts across departments, practice areas and firm sizes.
HMRC state that the purpose of the new regime is to ensure that:
“all tax advisers interacting with HMRC on behalf of their clients meet minimum standards. The changes will improve HMRC’s ability to monitor and exclude tax advisers who are objectively unable to meet HMRC’s Standards for Agents or cannot lawfully act as a tax adviser”[1].
In other words it is designed to ensure that HMRC knows who is interacting with it on behalf of taxpayers, that those advisers meet minimum standards, and that HMRC has the ability to restrict or remove access where standards are not met.
Client authority no longer sufficient
The core message is a simple one. HMRC is moving to an activity-based model. If a solicitor or law firm interacts with HMRC on a client’s behalf in relation to a tax matter, registration with HMRC will become a gateway requirement. This is not about whether a firm describes itself as a “tax adviser”. It is about what the firm actually does.
For many solicitors, this represents a cultural shift. Historically, professional status and client authority were enough. If a client instructed you to submit an SDLT return, an inheritance tax form or other tax-related documentation, that was treated as part of the legal service. HMRC is now saying, in effect, that this is no longer sufficient. From May 2026, subject to transitional arrangements, formal HMRC registration will be required before advisers can interact with HMRC on behalf of clients. Plans by HMRC to formally regulate tax advisers have been shelved in favour of the mandatory registration scheme which will be backed by new powers to monitor and disqualify those who are ‘objectively unable’ to meet its standards for agents.
Effect on work of a solicitor
Conveyancing is the most obvious example of where firms will be impacted by these changes. Submitting SDLT returns has always been treated as an integral part of the conveyancing process rather than as tax advice. Under the new regime, it is clearly an HMRC-facing activity that brings conveyancers squarely within scope. The consequences of getting this wrong are not theoretical. If a firm cannot submit SDLT returns because it is not properly registered, transactions stall, registrations are delayed, clients are exposed to penalties and complaints quickly follow.
Probate and private client work is in a very similar position. Solicitors who submit inheritance tax returns or correspond with HMRC on behalf of estates are also interacting directly with HMRC in relation to tax matters. Again, this has traditionally been seen as part of mainstream legal work. Under the new regime, it becomes a regulated interface that needs governance and oversight.
Beyond that, many firms will be affected in less obvious ways. Capital gains tax reporting, trust administration, corporate transactions involving stamp duties or reliefs, employment-related tax submissions and even pre-litigation correspondence with HMRC may all fall within scope, depending on how the work is structured. The idea that tax interaction is merely “incidental” to legal work is becoming harder to sustain.
Distinguished from AML requirements
One of the most important points to stress is what this regime is not. It is not AML registration. Most solicitors’ firms remain supervised for AML purposes by their legal regulator, and that does not change. Nor is this simply a matter of enrolling for an HMRC online service. While service enrolments such as Stamp Taxes Online remain relevant, mandatory registration goes further. It is about HMRC knowing who is interacting with it, applying minimum standards and retaining the ability to restrict or remove access if necessary.
That said, HMRC’s policy paper indicates that ongoing compliance with the registration conditions will include annual assurances, and it expressly references AML supervision status as part of minimum conditions (reflecting that many tax advisers must be AML-supervised somewhere). That does not mean that law firms suddenly become HMRC-supervised for AML; it means AML supervision status may be one of the conditions HMRC uses when deciding whether an adviser can be on the register and remain on it.
Risk
From a risk and compliance perspective, this matters because it turns HMRC interaction into a firm-wide governance issue. This is not something that can be left to individual fee earners or treated as a background administrative detail. Firms need to know where HMRC interaction arises, who is responsible for ensuring registration is in place, and how risks are identified and managed if registration is lost, delayed or restricted.
It is vital here that firms move away from last-minute compliance. May 2026 may sound some way off, but registration, governance and training all take time. Firms that wait until the regime is live to address this risk are likely to find themselves under pressure at exactly the wrong moment.
Who needs to register?
In practical compliance terms, any SRA-regulated practice that carries out any of the following activities should assume it is in-scope unless and until HMRC issues an express exception:
- Conveyancing – in particular Stamp Duty land Tax (SDLT) returns or capital gains tax (CGT),
- Probate and inheritance tax,
- Family work where it involves CGT, trust taxation, maintenance and lump sums,
- Trust administration and trust tax compliance,
- Corporate and commercial transactions with tax filings,
- Employment and share incentive work,
- Litigation and dispute resolution involving HMRC,
- Cross-border and international private client work, and
- Any other areas of work that involving interaction with HMRC.
Thus if a firm holds itself out as providing SDLT filing as part of conveyancing, including post-completion SDLT processing and payment arrangements tied to SDLT filing deadlines then it has a direct interaction with HMRC on behalf of a taxpayer and will be within scope of these provisions.
Failure to register with HMRC
Failing to register has both immediate practical consequences and wider regulatory implications. At a basic operational level, an unregistered firm may simply be unable to continue doing work it has historically undertaken, or may be unable to deliver that work in the way clients expect. Conveyancing is the clearest example. Firms that submit SDLT returns must be able to access HMRC’s Stamp Taxes Online / Stamp Taxes for Agents services. Without the necessary registration, enrolment may not be possible, meaning SDLT returns cannot be filed in the usual way. That in turn disrupts post-completion processes, including obtaining the SDLT5 certificate or UTRN required for Land Registry applications, with obvious knock-on effects for transactions, lenders and clients.
More broadly, HMRC has been explicit that advisers who interact with it on behalf of clients will be legally required to register and meet minimum standards before doing so. Once the regime is live, an unregistered firm – or an unregistered part of a firm – should expect to be unable to interact meaningfully with HMRC on client matters. HMRC’s policy materials also contemplate sanctions and suspension, and recognise that taxpayers may be adversely affected where their adviser can no longer act because registration conditions are not met. Beyond HMRC’s own enforcement powers, this should also be viewed through a regulatory lens. If a firm cannot deliver an agreed service because of a preventable compliance failure, it is exposed to complaints, negligence claims and conduct risk under the SRA framework. These are not tax penalties as such, but they are often more costly and damaging in practice.
How to register
As matters stand, HMRC has set out the legal framework and policy intent for registration, but has not yet published full, step-by-step practical guidance. What is clear is that from May 2026, subject to a transitional period of at least three months, registration will be mandatory for advisers interacting with HMRC on client tax matters.
HMRC has indicated that registration will be primarily digital, with a non-digital alternative for those who are digitally excluded, and that it is likely to sit alongside or build on existing HMRC online services. Reports also suggest that registration will be at firm level, with senior individuals identified as part of the process, and that firms will need to meet ongoing eligibility conditions such as being up to date with their own tax affairs and having appropriate AML supervision.
While the detailed mechanics are still awaited, firms should assume that registration will not be a last-minute tick-box exercise, but a structured process requiring planning, governance and senior oversight.
Practical Compliance Plan
The immediate compliance issue for firms is not simply whether registration is required, but how to ensure that work involving HMRC interaction remains deliverable, auditable and resilient once the new regime goes live. In practice, this means understanding exactly where HMRC interaction arises within the firm’s services, whether that is SDLT filing embedded in post-completion workflows, inheritance tax submissions in probate, or other tax-related correspondence handled by particular teams or systems.
Firms will also need to designate clear ownership of HMRC registration status at a senior level, because the regime anticipates ongoing eligibility checks and the possibility of sanction or suspension. That individual must be able to evidence continued compliance and respond promptly to HMRC queries.
At the same time, client-care documentation and scope of work should be reviewed to ensure that it accurately reflects what the firm does, particularly where services such as SDLT filing are continued, restructured or outsourced, as these are material aspects of the retainer.
Firms should also assume that HMRC registration will become a routine audit and assurance point. Clients, lenders and third parties are likely to ask whether the firm is properly authorised to submit tax returns on their behalf, and this will sit alongside existing expectations around SDLT and other HMRC-facing processes.
Sensible preparatory work can begin now, without waiting for final guidance. This includes confirming who controls HMRC enrolments and credentials, how authority to act is recorded, and how access is managed; allocating responsibility for monitoring the May 2026 rollout and completing registration during the transitional window; and making explicit, documented decisions about which HMRC-facing services the firm will continue to offer.
Crucially, these issues should be reflected in the firm’s risk register and operational controls, recognising that the inability to interact with HMRC is not a minor administrative issue but, in areas such as conveyancing, a completion-critical failure with direct client detriment potential.
Conclusion
The takeaway is straightforward. If your firm interacts with HMRC on behalf of clients in tax matters, you should assume registration will be required unless HMRC clearly says otherwise. This is not just a tax issue. It is a client-care, risk-management and service-delivery issue that deserves attention now.
Infolegal will continue to monitor developments closely and to update members with clear, practical guidance as the regime takes shape. As ever, our focus is on helping firms understand what is changing, why it matters, and how to deal with it sensibly and proportionately.
[1] https://www.gov.uk/government/publications/mandatory-tax-adviser-registration-with-hmrc/tax-advisers-to-register-with-hmrc-and-meet-minimum-standards